/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.values;



import com.bff.gaia.unified.sdk.transforms.ParDo;

import com.bff.gaia.unified.vendor.guava.com.google.common.base.MoreObjects;

import com.bff.gaia.unified.vendor.guava.com.google.common.collect.ImmutableList;



import java.io.Serializable;

import java.util.ArrayList;

import java.util.Collections;

import java.util.List;



/**

 * A {@link TupleTagList} is an immutable list of heterogeneously typed {@link TupleTag TupleTags}.

 * A {@link TupleTagList} is used, for instance, to specify the tags of the additional outputs of a

 * {@link ParDo}.

 *

 * <p>A {@link TupleTagList} can be created and accessed like follows:

 *

 * <pre>{@code

 * TupleTag<String> tag1 = ...;

 * TupleTag<Integer> tag2 = ...;

 * TupleTag<Iterable<String>> tag3 = ...;

 *

 * // Create a TupleTagList with three TupleTags:

 * TupleTagList tags = TupleTagList.of(tag1).and(tag2).and(tag3);

 *

 * // Create an empty TupleTagList:

 * Pipeline p = ...;

 * TupleTagList tags2 = TupleTagList.empty(p);

 *

 * // Get TupleTags out of a TupleTagList, by index (origin 0):

 * TupleTag<?> tagX = tags.get(1);

 * TupleTag<?> tagY = tags.get(0);

 * TupleTag<?> tagZ = tags.get(2);

 *

 * // Get a list of all TupleTags in a TupleTagList:

 * List<TupleTag<?>> allTags = tags.getAll();

 * }</pre>

 */

public class TupleTagList implements Serializable {

  /**

   * Returns an empty {@link TupleTagList}.

   *

   * <p>Longer {@link TupleTagList TupleTagLists} can be created by calling {@link #and} on the

   * result.

   */

  public static TupleTagList empty() {

    return new TupleTagList();

  }



  /**

   * Returns a singleton {@link TupleTagList} containing the given {@link TupleTag}.

   *

   * <p>Longer {@link TupleTagList TupleTagLists} can be created by calling {@link #and} on the

   * result.

   */

  public static TupleTagList of(TupleTag<?> tag) {

    return empty().and(tag);

  }



  /**

   * Returns a {@link TupleTagList} containing the given {@link TupleTag TupleTags}, in order.

   *

   * <p>Longer {@link TupleTagList TupleTagLists} can be created by calling {@link #and} on the

   * result.

   */

  public static TupleTagList of(List<TupleTag<?>> tags) {

    return empty().and(tags);

  }



  /**

   * Returns a new {@link TupleTagList} that has all the {@link TupleTag TupleTags} of this {@link

   * TupleTagList} plus the given {@link TupleTag} appended to the end.

   */

  public TupleTagList and(TupleTag<?> tag) {

    return new TupleTagList(

        new ImmutableList.Builder<TupleTag<?>>().addAll(tupleTags).add(tag).build());

  }



  /**

   * Returns a new {@link TupleTagList} that has all the {@link TupleTag TupleTags} of this {@link

   * TupleTagList} plus the given {@link TupleTag TupleTags} appended to the end, in order.

   */

  public TupleTagList and(List<TupleTag<?>> tags) {

    return new TupleTagList(

        new ImmutableList.Builder<TupleTag<?>>().addAll(tupleTags).addAll(tags).build());

  }



  /** Returns the number of TupleTags in this TupleTagList. */

  public int size() {

    return tupleTags.size();

  }



  /**

   * Returns the {@link TupleTag} at the given index (origin zero).

   *

   * @throws IndexOutOfBoundsException if the index is out of the range {@code [0..size()-1]}.

   */

  public TupleTag<?> get(int index) {

    return tupleTags.get(index);

  }



  /**

   * Returns an immutable List of all the {@link TupleTag TupleTags} in this {@link TupleTagList}.

   */

  public List<TupleTag<?>> getAll() {

    return tupleTags;

  }



  /////////////////////////////////////////////////////////////////////////////

  // Internal details below here.



  final List<TupleTag<?>> tupleTags;



  TupleTagList() {

    this(new ArrayList<>());

  }



  TupleTagList(List<TupleTag<?>> tupleTags) {

    this.tupleTags = Collections.unmodifiableList(tupleTags);

  }



  @Override

  public String toString() {

    return MoreObjects.toStringHelper(TupleTagList.class).add("tupleTags", tupleTags).toString();

  }

}